N tlim e fn tg 1 1 x jj 1 j 0 thus using

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Unformatted text preview: for data networks, we can consider the arrival rate to be in packets/sec. Let N t = number of packets in the link at time t Q – What is the average number of packets in the link? N = tlim E fN tg = !1 1 X  jj = 1 , =  ,  : j =0 Thus, using the steady-state probabilities, we can obtain the result for N . What about other measures such as average packet delay? To obtain this, we need the use the following result known as Little’s Law : CS 522, v 0.94, d.medhi, W’99 12 avg. number of packets in system in steady state (N) = avg. arrival rate * avg. packet delay in system in steady state (T) That is, N = T: Rearranging, we get 1 T = N= =  ,  = 1 ,  : Average waiting time in the queue, W , is W= Avg. waiting time in System – Avg. waiting time in Service 1 1 =  ,  ,  =  , : Again, by Little’s Law which is also applicable in queues, the average number of customers in queue is, 2 Nq = W = 1 , : Thus, we have shown above four performance measures that may be of interest for a network l...
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